THE INDICATIVE VALUE OF EARLY LIFE HISTORY PROCESSES OF FISH LARVAE FOR THE ENVIRONMENTAL QUALITY OF RIVERS.

Survival rates, developmental rates, growth and food energy partitioning in embryos, larvae and early juveniles of one of the most abundant rheophilic fish species (Chondrostoma nasus) in Europe were analyzed at different temperatures. From our studies it can be concluded, that embryos, larvae and early juveniles have many attributes which indicate a high reproductive potential and help to explain the previous success of the fish. Cruical factors are high survival rates and high efficiencies in energy conversion. A low spawning success, and low survival rates of young-of-the-year can therefore be attributed to unsuitable external factors.In this context, young C. nasus may therefore be considered as a good indicator of the environmental and ecological quality of river systems, both with regard to pollution and habitat alterations.